Supports routing of modulo operation (mod) based on value of cookie

[lianglli]

基于请求Cookie取模的流量切分，可以指定具体匹配的cookie，当cookie值取模运算得到余数满足关系运算符的匹配条件，则将请求转发到指定的upstream。

如果 [cookie值] mod [除数] 关系运算符 [余数] 为真，那么路由规则生效，请求就会被转发到指定的upstream。

取模除数: [2, 100]; 关系运算符: "==, >, >=, <, <="; 取模余数: [0, 取模除数)。

如果除数，关系运算符和余数的取值范围非法，则路由规则降级为基于请求Cookie的流量切分。

无损动态生效，无需tengine reload。

[lianglli]

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  annotations:
    nginx.ingress.kubernetes.io/canary: "true"
    nginx.ingress.kubernetes.io/canary-by-cookie: cookie-test3
    nginx.ingress.kubernetes.io/canary-mod-divisor: "100"
    nginx.ingress.kubernetes.io/canary-mod-relational-operator: '>'
    nginx.ingress.kubernetes.io/canary-mod-remainder: "5"
    nginx.ingress.kubernetes.io/ssl-redirect: "true"
  creationTimestamp: "2023-11-01T09:38:20Z"
  generation: 1
  name: tengine-ingress-hello-cookie-mod-ing
  namespace: default
  resourceVersion: "28551925"
  uid: b33335cd-0588-49ea-9648-180533a467aa
spec:
  ingressClassName: opensource-ingress
  rules:
  - host: echo.w1.com
    http:
      paths:
      - backend:
          service:
            name: tengine-ingress-echo3-service
            port:
              number: 80
        path: /
        pathType: Prefix
  tls:
  - hosts:
    - echo.w1.com
    secretName: https-server-1
status:
  loadBalancer: {}

...........................................................

$ curl -i -k --cookie "cookie-test3=1006" https://echo.w1.com
HTTP/2 200 
server: Tengine/3.1.0
date: Wed, 01 Nov 2023 09:38:52 GMT
content-type: text/plain; charset=utf-8
content-length: 7
strict-transport-security: max-age=0
ups-target-key: default-tengine-ingress-echo3-service-80
x-protocol: HTTP/2.0
alt-svc: h3=":443"; ma=2592000,h3-29=":443"; ma=2592000

echo ok